A compound having the following formula ##STR12## wherein X is selected from the group consisting of H, alkoxy radicals and halogen, R1 is selected from the group consisting of H and alkyl radicals, provided that at least one of X and R1 is other than H, R2 is selected from the group consisting of divalent hydrocarbon radicals, divalent substituted hydrocarbon radicals, oxo, divalent oxyhydrocarbo